WO2011148436A1 - Photoelectric conversion element and process for production thereof, and solid-state imaging element and process for production thereof - Google Patents

Abstract

In each of imaging pixels (10) in a solid-state imaging element, an insulating layer (101), a photoelectric conversion functional layer (111), a protective layer (112), a color filter layer (113) and a top lens layer (114) are laminated in this order on a substrate (100). The photoelectric conversion functional layer (111) is composed of a material containing an organic semiconductor material. In each of the imaging pixels (10), an pixel electrode (107) and a counter electrode (108) face to each other in an X-axis direction on the insulating layer (101).

Description

Photoelectric conversion element and manufacturing method thereof, and solid-state imaging element and manufacturing method thereof

The present invention relates to a photoelectric conversion element and a manufacturing method thereof, and a solid-state imaging element and a manufacturing method thereof, in particular, a photoelectric conversion element including a photoelectric conversion functional layer formed using a material containing an organic semiconductor material, and a manufacturing method thereof, and The present invention relates to a solid-state imaging device and a method for manufacturing the same.

A solid-state image pickup device mounted on a digital still camera, for example, a CMOS sensor or a CCD sensor has a plurality of two-dimensionally arranged photodiodes. Conventionally, each photodiode is configured by forming a PN junction in a semiconductor substrate.

Incidentally, in recent years, the pixel size has been reduced with the increase in the number of pixels, and the area of the photodiode region tends to be reduced. When the area of the photodiode region is reduced, there is a problem of a decrease in photoelectric conversion characteristics such as a decrease in sensitivity due to a decrease in aperture ratio and a decrease in light collection efficiency. Further, as described above, when a photoelectric conversion part is formed in a semiconductor substrate such as silicon, incident light is reflected / scattered by wirings formed above the semiconductor conversion part, resulting in a decrease in sensitivity due to light loss. Also, there arises a problem of color mixing due to the incidence of part of light on the photodiodes of adjacent pixels.

In order to solve such a problem, a solid-state imaging device including a photoelectric conversion functional layer including an organic semiconductor material, and the photoelectric conversion functional layer disposed above the wiring layer, that is, on the light incident side Has been proposed (see, for example, Patent Document 1). The configuration of the solid-state imaging device proposed in Patent Document 1 will be described with reference to FIG.

As shown in FIG. 20, a solid-state imaging device 901 according to the prior art includes an n region 904 and an n ⁺ region 905 for each pixel on a semiconductor substrate composed of an n-type silicon substrate 902 and a p well layer 903 having a plurality of pixels. Is formed. Further, an insulating layer 906 is formed on the n-type silicon substrate 902, and a transparent electrode 907 corresponding to each pixel of the n-type silicon substrate 902 is formed on the insulating film 906. The transparent electrode 907 and the n ⁺ region 905 are connected to each other by a contact portion 908 embedded in the insulating film 906 for each pixel.

On the transparent electrode 907, a photoelectric conversion portion 909, an upper electrode 910, and protective films 911 and 912 are formed over a plurality of pixels. An R (red), G (green), and B (blue) color filter 913 and a microlens 914 are formed on the protective film 912 for each pixel.

Further, in paragraph [0143] in the specification of Patent Document 1, when a predetermined bias voltage is applied to the transparent electrode 907 and the upper electrode 910, the charge generated in the photoelectric conversion unit 909 is transferred to the transparent electrode 907 and the contact unit 908. It moves to the n ⁺ area | region 905 via it, and is accumulate | stored.

JP 2009-130090 A JP 2006-245045 A

However, in the solid-state imaging device proposed in Patent Document 1, the upper electrode 910 is disposed above the photoelectric conversion unit 909 where photoelectric conversion is performed, that is, on the light incident side. Is blocked by the upper electrode 910. For this reason, the solid-state imaging device proposed in Patent Document 1 is required to further improve sensitivity.

Here, as a constituent material of the upper electrode 910, for example, ITO (indium tin oxide) or IZO (indium zinc oxide) is used, but its light transmittance is not 100%. The light transmittance in such a transparent electrode film has been studied in, for example, Patent Document 2, and at least several [%], and in the case of many, several tens [%] cannot be transmitted.

The present invention has been made in order to solve the above-described problems, and an object thereof is to provide a high-sensitivity photoelectric conversion element with little optical loss and a manufacturing method thereof, and a solid-state imaging element and a manufacturing method thereof. And

In order to achieve the above object, the present invention adopts the following configuration.

(1) The photoelectric conversion element according to the present invention is in a state of being in contact with the interface in the photoelectric conversion functional layer, the substrate, the photoelectric conversion functional layer formed above the substrate, and including the organic semiconductor material. A first electrode and a second electrode are provided. In the photoelectric conversion element according to the present invention, the first electrode is in contact with the interface on the substrate side in the photoelectric conversion functional layer, and the first electrode and the second electrode are in the thickness direction of the substrate. In the crossing direction, they are opposed to each other.

(2) In the photoelectric conversion element according to the present invention, in the configuration of (1) above, the photoelectric conversion functional layer is formed in a state of covering the upper surface and the side surface of the first electrode, and the second electrode is the thickness of the substrate. In a direction intersecting with the direction, the first electrode is arranged so as to surround at least a part of the periphery of the first electrode.

(3) The photoelectric conversion element according to the present invention is configured as described in (1) above, in which the first electrode is composed of a plurality of electrode elements arranged at intervals from each other in a direction along the main surface of the substrate. The second electrode is arranged so as to surround at least a part of the plurality of electrode elements in a direction intersecting the thickness direction of the substrate.

(4) The photoelectric conversion element according to the present invention is characterized in that, in the configuration of (2), the first electrode in the thickness direction of the substrate is not covered with the second electrode.

(5) The photoelectric conversion element according to the present invention has a stacked structure in which the photoelectric conversion functional layer includes a photoelectric conversion layer and at least one of an electron transport layer and a hole transport layer in the configuration of (1) above. It is characterized by being comprised.

(6) The photoelectric conversion element according to the present invention is characterized in that, in the configuration of (1), the surface of at least one of the first electrode and the second electrode is a light reflecting surface.

(7) In the photoelectric conversion element according to the present invention, in the configuration of (1) above, a protective layer for protecting the photoelectric conversion functional layer is laminated on the photoelectric conversion functional layer in the thickness direction of the substrate. It is characterized by.

(8) In the photoelectric conversion element according to the present invention, in the configuration of (1) above, a color filter layer made of an organic material is laminated above the photoelectric conversion functional layer in the thickness direction of the substrate. It is characterized by.

(9) The photoelectric conversion element according to the present invention is characterized in that, in the configuration of (1), the layer thickness of the second electrode in the thickness direction of the substrate is thicker than the layer thickness of the first electrode.

(10) The solid-state imaging device according to the present invention has a plurality of imaging pixel units arranged two-dimensionally, and each of the plurality of imaging pixel units is any one of the photoelectric conversion devices according to (1) to (9) above. It is characterized by including the following structure.

(11) The method for producing a photoelectric conversion element according to the present invention includes the following steps.

(I) Step of forming the first electrode and the second electrode: forming the first electrode and the second electrode in a state of facing each other in a direction intersecting the thickness direction of the substrate above the substrate .

(Ii) Step of forming a photoelectric conversion functional layer: Using a material containing an organic semiconductor material, the photoelectric conversion functional layer is formed in contact with both the first electrode and the second electrode.

(12) In the method for manufacturing a photoelectric conversion element according to the present invention, in the step (11), in the step of forming the first electrode and the second electrode, in the direction intersecting the thickness direction of the substrate, Forming the photoelectric conversion functional layer in a state of covering the upper surface and the side surface of the first electrode in the step of forming the two electrodes in a state of surrounding at least a part of the periphery of the first electrode and forming the photoelectric conversion functional layer; It is characterized by.

(13) In the method for manufacturing a photoelectric conversion element according to the present invention, in the configuration of (11) above, in the step of forming the first electrode and the second electrode, in the direction along the main surface of the substrate, the photoelectric conversion element is spaced from each other. The first electrode is formed with a plurality of electrode elements formed in an open state, and the second electrode is formed so as to surround at least a part of the plurality of electrode elements in the first electrode. To do.

(14) In the method for manufacturing a photoelectric conversion element according to the present invention, in the configuration of (12) above, in the step of forming the first electrode and the second electrode, the upper part of the first electrode is covered in the thickness direction of the substrate. The second electrode is formed so as not to exist.

(15) The method for producing a photoelectric conversion element according to the present invention includes, in the step (11), a step of forming a photoelectric conversion functional layer, including a photoelectric conversion layer and at least an electron transport layer and a hole transport layer. A photoelectric conversion functional layer is formed with a stacked structure including one of the layers.

(16) In the method for manufacturing a photoelectric conversion element according to the present invention, in the step (11), in the step of forming the first electrode and the second electrode, at least one of the first electrode and the second electrode is The surface is formed so as to be a light reflecting surface.

(17) In the method for producing a photoelectric conversion element according to the present invention, in the configuration of (11) above, a protective layer for protecting the photoelectric conversion functional layer is laminated on the photoelectric conversion functional layer in the thickness direction of the substrate. It is characterized by comprising a forming step.

(18) The method for producing a photoelectric conversion element according to the present invention includes a step of laminating and forming a color filter layer above the photoelectric conversion functional layer in the thickness direction of the substrate in the configuration (11) above using an organic material. It is characterized by providing.

(19) The method for producing a photoelectric conversion element according to the present invention is the step of forming the first electrode and the second electrode in the configuration of (11) above, wherein the second electrode has a layer thickness in the thickness direction of the substrate. Is formed so as to be thicker than the first electrode.

(20) A method for manufacturing a solid-state imaging device according to the present invention is a method for manufacturing a solid-state imaging device having a plurality of imaging pixel units arranged two-dimensionally. ) To (19) according to any one of the methods for producing a photoelectric conversion element.

According to the present invention, it is possible to provide a photoelectric conversion device and a solid-state imaging device having high sensitivity by eliminating light loss due to electrodes and a method for manufacturing the same.

In the configuration of (1), the first electrode and the second electrode are opposed to each other in the direction intersecting the thickness direction of the substrate, and the first and second electrodes are opposed to the interface of the photoelectric conversion function layer. Both sides touch. The first electrode is in contact with the interface on the substrate side in the photoelectric conversion functional layer. For this reason, in the photoelectric conversion element according to the present invention, since the top of the photoelectric conversion function layer is not covered with one electrode, there is no loss of incident light to the photoelectric conversion function layer, and the electrode on the photoelectric conversion function layer There is no process damage accompanying the formation.

Therefore, the photoelectric conversion element according to the present invention has high optical sensitivity with little optical loss.

Note that, as described in (10) above, the solid-state imaging device according to the present invention has the same effects as the above because each of the plurality of imaging pixel units is formed including the configuration of the photoelectric conversion device according to the present invention. Can play.

In the configuration (2) or (3), the second electrode is formed so as to surround at least a part of the periphery of the first electrode in the direction intersecting the thickness direction of the substrate. The electric field strength in the conversion functional layer is increased, and the photoelectric conversion characteristics can be improved.

In the configuration of (5) above, the photoelectric conversion functional layer is configured with a stacked structure having functional layers such as an electron transport layer and a hole transport layer in addition to the photoelectric conversion layer. Charge transfer characteristics, photoelectric conversion characteristics, and the like can be improved.

In the configuration of (6) above, since at least one of the first electrode and the second electrode has a light reflecting surface, incident light can be reflected on the electrode surface and incident again on the photoelectric conversion function layer. And the sensitivity can be further improved.

In the configuration of (7) above, since a protective layer is laminated on the photoelectric conversion function layer, the organic layer is formed by moisture or gas (oxygen) in the process after the formation of the photoelectric conversion function layer made of an organic semiconductor material. Degradation of the semiconductor material can be prevented. Therefore, when this configuration is adopted, the protective layer is formed immediately after the photoelectric conversion functional layer is formed, so that the effect of preventing damage in the subsequent steps is great.

Furthermore, even after the photoelectric conversion element is completed, aged deterioration of the photoelectric conversion functional layer made of an organic semiconductor material due to moisture or gas (oxygen) can be prevented. In addition, by covering the photoelectric conversion functional layer with a protective layer, the photoelectric conversion functional layer including the organic semiconductor can be protected from organic solvents, plasma, and the like, so that subsequent processes such as color filter formation are facilitated.

In the configuration (8), even when the photoelectric conversion functional layer has a broad absorption spectrum in the visible region, it is possible to provide a solid-state imaging device that is particularly excellent in spectral characteristics and compatible with RGB.

In the configuration of (9), the layer thickness of the second electrode is made larger than the layer thickness of the first electrode, so that the region that contributes to photoelectric conversion is increased in the photoelectric conversion function layer to improve the photoelectric conversion characteristics. be able to.

Moreover, the manufacturing method of the photoelectric conversion element and the manufacturing method of a solid-state image sensor which concern on this invention are the photoelectric conversion element and solid-state image sensor which concern on this invention which has said effect like said (11) to (20). It can be manufactured reliably.

In addition, neither the first electrode nor the second electrode needs to be a transparent electrode, and the first electrode and the second electrode can be formed in the same process, and the manufacturing cost can be reduced by manufacturing with a simple process. Can be kept low.

1 is a schematic plan view showing a schematic configuration of a solid-state imaging element 1 according to Embodiment 1. FIG. 2 is a schematic cross-sectional view showing a partial configuration of an imaging pixel region 1a in the solid-state imaging device 1. FIG. 3 is a schematic cross-sectional view showing an electric field strength distribution in a photoelectric conversion functional layer 111 in the solid-state imaging device 1. FIG. 6 is a schematic cross-sectional view showing a partial configuration of an imaging pixel region in a solid-state imaging device according to Embodiment 2. FIG. 6 is a schematic cross-sectional view showing an electric field strength distribution in a photoelectric conversion function layer 116 in the solid-state imaging device according to Embodiment 2. FIG. 10 is a schematic plan view showing the shapes of pixel electrodes 207 and counter electrodes 208 in the solid-state imaging device according to Modification 1 and their arrangement with each other. FIG. FIG. 10 is a schematic plan view showing shapes and arrangement of pixel electrodes 307 and counter electrodes 308 in a solid-state imaging device according to Modification 2. It is a schematic plan view which shows the shape of the pixel electrode 407 and the counter electrode 408 in a solid-state image sensor which concerns on the modification 3, and mutual arrangement | positioning. FIG. 10 is a schematic plan view showing the shape of a pixel electrode 507 and a counter electrode 508 and their arrangement in a solid-state imaging device according to Modification 4. FIG. 16 is a schematic plan view showing the shapes of pixel electrodes 607 and counter electrodes 608 and their mutual arrangement in a solid-state imaging device according to Modification 5. 14 is a schematic plan view showing shapes and arrangement of pixel electrodes 707 and counter electrodes 708 in a solid-state imaging device according to Modification 6. FIG. FIG. 16 is a schematic plan view showing the shape of a pixel electrode 807 and a counter electrode 808 in the solid-state imaging device according to Modification Example 7 and the arrangement of each other. FIG. 16 is a schematic plan view showing the shape of a pixel electrode 907 and a counter electrode 908 and their arrangement in a solid-state imaging device according to Modification 8. It is a schematic plan view showing the shape of the pixel electrode 1207 and the counter electrode 1208 in the solid-state imaging device according to Modification 9 and the arrangement of each other. 6 is a schematic cross-sectional view illustrating a partial configuration of an imaging pixel region in a solid-state imaging device according to Embodiment 3. FIG. 6 is a schematic cross-sectional view showing an electric field intensity distribution in a photoelectric conversion function layer 131 in a solid-state imaging device according to Embodiment 3. FIG. FIGS. 9A to 9C are schematic process diagrams illustrating a part of the manufacturing process of the solid-state imaging device according to the third embodiment. (A) And (b) is a schematic process drawing which shows a part of manufacturing process of the solid-state image sensor which concerns on Embodiment 3. FIG. 6 is a schematic cross-sectional view showing a partial configuration of an imaging pixel region in a solid-state imaging device according to Embodiment 4. FIG. It is a schematic cross section which shows a partial structure of the imaging pixel area | region in the solid-state image sensor which concerns on a prior art.

[Outline of photoelectric conversion device and solid-state imaging device according to the present invention]
The photoelectric conversion element includes an electromagnetic wave absorption / photoelectric conversion site and a charge accumulation / transfer / readout site for charges generated by photoelectric conversion.

The electromagnetic wave absorption / photoelectric conversion site is made of at least one organic semiconductor material that can absorb and photoelectrically convert at least blue, green, and red light. The blue light absorption part (hereinafter referred to as B absorption part) can absorb at least light of 400 [nm] to 500 [nm], and preferably the absorption factor of the peak wavelength in that wavelength region is 50 [% ] That's it. The green light absorption part (hereinafter referred to as G absorption part) can absorb at least light of 500 [nm] to 600 [nm], and preferably the absorption factor of the peak wavelength in the wavelength region is 50 [%]. That's it. The red light absorption site (hereinafter referred to as R-absorbing portion) can absorb at least light of 600 [nm] to 700 [nm]. Preferably, the absorption factor of the peak wavelength in the wavelength region is 50 [% ] That's it.

In the electromagnetic wave absorption / photoelectric conversion part, the B absorption part, the G absorption part, and the R absorption part may each form a layer. Alternatively, a single layer may be formed of a plurality of organic semiconductor materials, and the B absorption portion, G absorption portion, and R absorption portion may be included in one layer, or a broad absorption spectrum in the visible region. You may have.

The charge storage / transfer / readout part is preferably formed under the electrode and shielded by the electrode, so that a false signal (color mixture) due to the influence of light can be prevented. Preferably, it is formed in and on the surface of an inorganic semiconductor substrate such as silicon.

A photoelectric conversion layer made of a material containing an organic semiconductor material in the present invention will be described.

The electromagnetic wave absorption / photoelectric conversion site of the present invention is composed of a layer made of a material including an organic semiconductor material formed on a pair of electrodes (first electrode and second electrode). The photoelectric conversion functional layer is formed by laminating or mixing a part that absorbs electromagnetic waves, a photoelectric conversion part, an electron transport part, a hole transport part, and the like. The organic semiconductor layer preferably contains an organic p-type compound (p-type semiconductor layer) or an organic n-type compound (n-type semiconductor layer).

Organic p-type compounds (organic p-type semiconductors) are donor organic compounds (semiconductors), which are mainly represented by hole-transporting organic compounds and refer to organic compounds that have the property of easily donating electrons. More specifically, an organic compound having a smaller ionization potential when two organic materials are used in contact with each other.

Accordingly, any organic compound can be used as the donor organic compound as long as it is an electron-donating organic compound. For example, there are phthalocyanine compounds. Of course, the present invention is not limited thereto, and as described above, any organic compound having an ionization potential smaller than that of the organic compound used as the n-type (acceptor property) compound may be used as the donor organic semiconductor.

Organic n-type compounds (organic n-type semiconductors) are acceptor organic compounds (semiconductors), which are mainly represented by electron-transporting organic compounds and refer to organic compounds that easily accept electrons. More specifically, the organic compound having the higher electron affinity when two organic materials are used in contact with each other.

Accordingly, any organic compound can be used as the acceptor organic compound as long as it is an electron-accepting organic compound. For example, there is a tetracene derivative. Of course, the present invention is not limited to this, and any organic compound having an electron affinity higher than that of the organic compound used as the donor organic compound as described above may be used as the acceptor organic semiconductor.

It has at least one of an organic p-type semiconductor and an organic n-type semiconductor on a pair of electrodes (first electrode and second electrode). When both an organic p-type semiconductor and an organic n-type semiconductor are provided, a p-type semiconductor layer and an n-type semiconductor layer may be formed, respectively, or they may be mixed and dispersed to form one layer. In the case of mixing / dispersing, by incorporating a bulk heterojunction structure in the organic layer, the disadvantage that the carrier diffusion length of the organic layer is short can be compensated and the photoelectric conversion characteristics can be improved.

In the case of a conventional stacked photoelectric conversion element, the thickness of the organic semiconductor layer is preferably as thick as possible in terms of light absorption. However, in terms of separation of electron-hole pairs, the thickness of the photoelectric conversion functional layer is not limited. It is preferable to reduce the thickness and increase the electric field strength in the layer when a voltage is applied between the electrodes. In the present invention, a pair of electrodes (first electrode and second electrode) are formed in a plane (direction intersecting the thickness direction of the substrate), and a photoelectric conversion function layer is formed thereon, so that the photoelectric conversion function The electric field strength in the layer is not uniform, and the region closer to the electrode has higher electric field strength and higher photoelectric conversion efficiency.

Also, the closer to the incident surface, that is, the region closer to the surface (upper surface) of the photoelectric conversion functional layer, the greater the amount of light absorption, and more electric charge is generated. In consideration of these, in the case of the planar photoelectric conversion element and the solid-state imaging element in the present invention, the thinner the photoelectric conversion functional layer, the higher the photoelectric conversion characteristics. The range suitable for the film thickness of the organic semiconductor layer formed on the electrode varies depending on conditions such as the material of the organic semiconductor and voltage, but is preferably 20 nm or more and 500 nm or less, and more preferably 20 nm or less. nm] or more and 300 [nm] or less, and particularly preferably 20 [nm] or more and 200 [nm] or less.

The photoelectric conversion functional layer according to the present invention is formed by a dry film forming method or a wet film forming method. Specific examples of the dry film forming method include a vacuum vapor deposition method, a sputtering method, an ion plating method, a physical vapor deposition method such as an MBE method, or a CVD method such as plasma polymerization. When one layer is formed by mixing and dispersing an organic p-type semiconductor and an organic n-type semiconductor, a flash vapor deposition method or the like can also be used. As the wet film formation method, a casting method, an ink jet method, a spin coating method, a dipping method, an LB method, or the like can be used.

When a high molecular compound is used as the organic compound, it is preferable to form a film by a wet film forming method that is easy to create because the high molecular compound may be decomposed by a dry film forming method such as vapor deposition. On the other hand, when a low molecule is used, a dry film forming method is preferably used, and a vacuum deposition method is particularly preferably used.

Next, the electrode according to the present invention will be described.

It consists of two electrodes, a first electrode and a second electrode (one is a pixel electrode and the other is a counter electrode). The photoelectric conversion functional layer is formed thereon. Electrons and holes generated and separated by the photoelectric conversion functional layer move toward the first electrode or the second electrode, respectively. Preferably, electrons move to the first electrode (pixel electrode) and holes move to the second electrode (counter electrode).

When holes move to the second electrode (counter electrode), holes are extracted from the photoelectric conversion functional layer to the second electrode (counter electrode). Preferably, holes are taken out from the hole transport photoelectric conversion layer or the hole transport layer.

When electrons move to the first electrode (pixel electrode), the electrons are taken out from the photoelectric conversion function layer to the first electrode (pixel electrode). Preferably, electrons are taken out from the electron transporting photoelectric conversion layer or the electron transport layer.

As a material of the electrode, a metal, an alloy, a metal oxide, an electrically conductive compound, or a mixture thereof can be used. A material having a high light reflectance such as aluminum is preferable. Thereby, incident light is reflected on the electrode surface by the electrode, and the sensitivity can be improved by allowing the light to enter the photoelectric conversion functional layer again.

The film thickness of the electrode can be appropriately selected depending on the material. In order to suppress the leakage of light to a semiconductor substrate such as silicon forming the charge accumulation / transfer / readout part, it is preferable to increase the film thickness of the electrode to sufficiently generate the reflection / absorption of light. Usually, it is 10 [nm] or more and 1 [μm] or less, and preferably 200 [nm] or more and 500 [nm] or less. In addition, when a photoelectric conversion function layer is inserted between the first electrode (pixel electrode) and the second electrode (counter electrode), the photoelectric conversion function layer may be thicker than the electrode. preferable.

For forming the electrode, various methods are used depending on the material. For example, when aluminum is used, a film forming method such as a sputtering method can be used. The formed aluminum film can be formed into a desired electrode shape by a photolithography method and an etching method which are used for manufacturing a normal inorganic semiconductor element.

Further, for example, when copper (Cu) or a copper alloy is used, a dual damascene structure in which copper (Cu) or a copper alloy is formed in a recess formed in the insulating film can be adopted. Details regarding the dual damascene are described in, for example, Japanese Patent No. 3217319, and therefore detailed description thereof is omitted here.

Also, since both the first electrode (pixel electrode) and the second electrode (counter electrode) are formed below the photoelectric conversion functional layer, it is not necessary to use a transparent electrode such as ITO.

When the film thicknesses of the first electrode (pixel electrode) and the second electrode (counter electrode) are different, each electrode can be created as follows.

For example, when the first electrode (pixel electrode) is thinner than the second electrode (counter electrode), first, a photoresist is formed in the same pattern as the desired first electrode (pixel electrode), A film made of copper (Cu) or a copper alloy is formed thereon. Polishing is performed by CMP or the like until the first electrode (pixel electrode) has a desired film thickness, and the photoresist is removed to form the first electrode (pixel electrode).

Further, similarly, a photoresist is formed in the same pattern as a desired second electrode (counter electrode), and a film made of copper (Cu) or a copper alloy is formed thereon. Polishing is performed by CMP or the like until the second electrode (counter electrode) has a desired thickness. At this time, the second electrode (counter electrode) is polished so as not to damage the first electrode (pixel electrode). Needs to be thicker than the first electrode (pixel electrode). Then, the second electrode (counter electrode) is formed by removing the photoresist.

The larger the film thickness difference between the first electrode (pixel electrode) and the second electrode (counter electrode), the easier it is to form an electrode, and even in the photoelectric conversion function layer, the upper region away from the first electrode (pixel electrode) In addition, a stronger electric field strength is added to the thickness of the second electrode (counter electrode), and the photoelectric conversion characteristics can be improved.

The layer thickness difference between the first electrode (pixel electrode) and the second electrode (counter electrode) can be appropriately set according to the thickness of the organic semiconductor material or the desired solid-state imaging device, but preferably, 50 [nm] or more and 200 [nm] or less.

Between the first electrode (pixel electrode) and the second electrode (counter electrode), a photoelectric conversion functional layer made of an organic semiconductor may be inserted, or an insulating layer may be inserted. When the photoelectric conversion functional layer is interposed, the strongest electric field strength is applied to the photoelectric conversion functional layer in the portion sandwiched between the first electrode (pixel electrode) and the second electrode (counter electrode) (see FIG. 3). . For this reason, high photoelectric conversion efficiency is obtained in the corresponding photoelectric conversion functional layer. Therefore, when the film thickness of the photoelectric conversion functional layer on the electrode is thin, the photoelectric conversion functional layer is interposed between the first electrode (pixel electrode) and the second electrode (counter electrode). Is good.

In addition, since the portion between the first electrode (pixel electrode) and the second electrode (counter electrode) has the shortest inter-electrode distance and a strong electric field is applied, the electrode and the photoelectric conversion functional layer between the electrodes should be thickened. Is preferred.

On the other hand, FIG. 5 shows a conceptual diagram of lines of electric force in the photoelectric conversion element when an insulating layer is interposed between the first electrode (pixel electrode) and the second electrode (counter electrode). The electric field is not concentrated in the region sandwiched between the first electrode (pixel electrode) and the second electrode (counter electrode), and a strong electric field is also applied to the photoelectric conversion functional layer on the electrode. The film thickness of the photoelectric conversion functional layer can be increased.

The distance between the first electrode (pixel electrode) and the second electrode (counter electrode) can be set as appropriate depending on the electrode material and the forming method. The shorter the distance, the electrode when a constant voltage is applied. The electric field strength between them becomes stronger. In addition, since the area ratio of the electrode in the imaging pixel increases and the amount of reflection or absorption of incident light increases, the distance between the first electrode (pixel electrode) and the second electrode (counter electrode) is preferably 50 [nm. ] To 300 [nm] or less.

The first electrode (pixel electrode) is an electrode created above the substrate on which the charge accumulation / transfer / readout part is formed, and the signal charge generated by the photoelectric conversion function layer is the first electrode (pixel electrode). To move to a charge storage site formed in the substrate. A circuit for storing / transferring / reading out charges is formed in the substrate and on the surface for each pixel (one image pickup pixel). When the first electrode (pixel electrode) is usually formed for each pixel, or when the first electrode (pixel electrode) in one pixel is divided into several electrode elements to form one set One set of first electrodes (pixel electrodes) is formed for each pixel.

The second electrode (counter electrode) has a function of discharging charges having a polarity opposite to the signal charge taken in by the first electrode (pixel electrode). Since the discharge of the electric charge does not need to be divided between the imaging pixels, the second electrode (counter electrode) can be shared between the imaging pixels.

As the planar shape of the first electrode (pixel electrode) and the second electrode (counter electrode), the second electrode (counter electrode) is formed so as to surround the first electrode (pixel electrode), so that the entire photoelectric conversion functional layer is formed. An electric field can be applied. For example, as shown in FIG. 6, a shape in which the second electrode (counter electrode) is formed in a lattice shape and the first electrode (pixel electrode) formed in a square shape is arranged therein may be considered.

It is not always necessary to surround the entire periphery of the first electrode (pixel electrode) with the second electrode (counter electrode), and the cleaning liquid after the electrode is formed can be effectively removed to remove image defects such as stains. In order to suppress this, only a part of the periphery of the first electrode (pixel electrode) may be surrounded by the second electrode (counter electrode). For example, the second electrode (counter electrode) may have a planar shape as shown in FIG. 7 or FIG.

Further, the planar shape of the first electrode (pixel electrode) and the second electrode (counter electrode) may be formed so as to increase the facing area between the first electrode (pixel electrode) and the second electrode (counter electrode). Thus, by increasing the facing area, it is possible to increase a region to which a strong electric field strength is applied and increase photoelectric conversion efficiency. In particular, since a stronger electric field is generated at the end of the electrode, when the planar shape of the first electrode (pixel electrode) is a square, the electric field strength is weak at the center of the first electrode (pixel electrode), and the photoelectric conversion efficiency. For example, as shown in FIG. 9, the planar shape of the first electrode (pixel electrode) is made concave, and the second electrode (counter electrode) is interposed between the concave portions of the first electrode (pixel electrode). It may be a planar shape in which a part of is inserted. Also in this case, it is not always necessary to surround the entire periphery of the first electrode (pixel electrode) with the second electrode (counter electrode), and only a part of the periphery of the first electrode (pixel electrode) is the second electrode (counter electrode). You may enclose with. For example, the second electrode (counter electrode) may have a planar shape as shown in FIG. 10 or FIG.

Furthermore, the first electrode (pixel electrode) is composed of a plurality of electrode elements, and a part of the second electrode (counter electrode) is inserted between each electrode element, whereby the first electrode The facing area between the (pixel electrode) and the second electrode (counter electrode) can also be increased. For example, as shown in FIG. 12, the first electrode (pixel electrode) may be configured from four electrode elements, and the second electrode (counter electrode) may be disposed so as to surround them. Also in this case, the entire periphery of the first electrode (pixel electrode) is not necessarily surrounded by the counter electrode, and only a part of the periphery of the first electrode (pixel electrode) may be surrounded by the second electrode (counter electrode). For example, the second electrode (counter electrode) may have a planar shape as shown in FIG.

The above shows preferred forms of the present invention, but of course not limited to this, and any flat shape may be used as long as it falls under the above concept.

The voltage applied to the photoelectric conversion functional layer made of a material containing an organic semiconductor may be any voltage, and is necessary depending on the organic semiconductor material, the film thickness, the distance between the first electrode (pixel electrode) and the second electrode (counter electrode), etc. The appropriate voltage can be changed as appropriate.

The photoelectric conversion efficiency improves as the electric field strength applied to the photoelectric conversion functional layer increases, but the electric field strength increases as the distance between the first electrode (pixel electrode) and the second electrode (counter electrode) becomes shorter even at the same applied voltage. Therefore, if the distance between the first electrode (pixel electrode) and the second electrode (counter electrode) is short, the applied voltage may be relatively small.

The electric field strength applied to the photoelectric conversion functional film is preferably 10 [V / m] or more, more preferably 1 × 10 ³ [V / m] or more, and further preferably 1 × 10 ⁵ [ V / m] or more, particularly preferably 1 × 10 ⁶ [V / m] or more, and most preferably 1 × 10 ⁷ [V / m] or more. Although there is no particular upper limit, if the electric field strength is increased too much, damage to the organic semiconductor occurs, and an electric current flows unfavorably even in a dark place, so 1 × 10 ¹² [V / m] or less is preferable. × 10 ⁹ [V / m] or less is preferable.

Regarding the charge storage / transfer / readout part, reference can be made to JP-A-58-103165, JP-A-58-103166, JP-A-2003-332551, and the like. A structure in which a MOS transistor is formed for each imaging pixel on a semiconductor substrate or a structure having a CCD as an element can be used as appropriate. For example, in the case of a photoelectric conversion element using a MOS transistor, charge is photogenerated in the photoelectric conversion functional layer by incident light, and the electric charge is generated by the electric field generated in the photoelectric conversion functional layer by applying a voltage to the electrode. And further move to the charge storage portion in the semiconductor substrate to accumulate charges.

The charge accumulated in the charge accumulation unit is transferred to the charge readout unit by switching of the MOS transistor, and is further read as an electric signal and output to an external circuit. As a result, the image signal is input to the solid-state imaging device including the signal processing unit.

A normal color readout circuit can be used for signal readout. A signal charge or a signal current / voltage generated by photoelectric conversion in the light receiving unit is stored in the light receiving unit itself or an attached capacitor. The stored electric charge is read out together with the selection of the image pickup pixel position by a technique of a MOS type image pickup device using an XY address method, a so-called CMOS sensor.

In addition, as an address selection method, there is a method in which each pixel is sequentially selected by a multiplexer switch and a digital shift register and read as a signal voltage (or signal charge) to a common output signal line. An image sensor for XY address operation that is two-dimensionally arrayed is known as a CMOS sensor. This is because the switch provided in the pixel connected to the intersection of X and Y is connected to the vertical shift register, and when the switch is turned on by the voltage from the vertical scanning shift register, it is read from the pixel provided in the same row. The signal is read out to the output line in the column direction. This signal is sequentially output through a switch driven by a horizontal scanning shift register. For reading out the output signal, a floating diffusion detector or a floating gate detector can be used. For signal processing, signal processing such as gamma correction by an ADC circuit or digitization by an AD converter can be performed.

A semiconductor material with high charge mobility is used for the charge transfer / readout part. Among these, a silicon semiconductor is preferable because of the progress in miniaturization technology and low cost. There are many methods for charge transfer / reading, but any method may be used, preferably a CMOS method or a CCD method. Further, the CMOS method is often preferable in terms of high-speed reading, pixel addition, partial reading, low power consumption, and the like.

Any metal may be used for the plurality of contact hole portions connecting the photoelectric conversion functional layer / first electrode (pixel electrode) and the charge accumulation / transfer / readout portion, and copper, aluminum, silver, gold, chromium, tungsten Alternatively, it is preferable to use these alloys. For example, when the first electrode (pixel electrode) is formed using copper, the contact material in the upper contact hole may be copper, and the contact material in the lower contact hole connected to the semiconductor substrate may be tungsten. It is necessary to form a contact hole between the first electrode (pixel electrode) and the charge accumulation portion for each pixel. When the first electrode (pixel electrode) is composed of a plurality of electrode elements, contact holes are formed in all the divided electrode elements.

As the protective layer, a protective layer made of an inorganic material formed in a vacuum by a dry film forming method on the photoelectric conversion functional layer is preferable. The protective layer protects the photoelectric conversion functional layer made of a material containing an organic semiconductor from heating, water, organic solvent, plasma, etc. in the process after the protective layer is formed, and also shuts off moisture, gas, etc. after manufacturing and deteriorates over time. There is a role to suppress.

Furthermore, since the protective layer is formed on the photoelectric conversion functional layer, it is preferable that the protective layer has high transparency in order to suppress the loss of incident light as much as possible.

Further, a production method in which the photoelectric conversion functional layer is less damaged when the protective layer is formed is preferable. For example, inductively coupled plasma CVD (ICPCVD) generates a high-density plasma at room temperature, and can form a very good protective layer at room temperature as compared with normal plasma CVD. Since it is formed at room temperature, deterioration of the photoelectric conversion functional layer can be suppressed, and since plasma is generated at a position sufficiently away from the substrate, damage due to plasma can be suppressed.

Further, for example, even in electron cyclotron resonance plasma CVD (ECRCVD), high-density plasma is generated at room temperature, and an extremely high-quality protective layer can be formed at room temperature as compared with normal plasma CVD. Again, since it is formed at room temperature, deterioration of the photoelectric conversion functional layer can be suppressed, and plasma is generated at a position sufficiently away from the substrate, so that damage due to plasma can also be suppressed. By these film forming methods, a highly transparent inorganic material such as silicon oxide or silicon nitride is formed as a protective layer.

The protective properties of the protective layer increase as the film thickness increases, but the transparency decreases. The thickness of the protective layer is preferably 100 [nm] or more and 500 [nm] or less.

When the light absorption part of the photoelectric conversion functional layer has broad absorption with respect to the visible region, it is preferable to form a color filter. When manufacturing a solid-state imaging device corresponding to full color, color filters corresponding to RGB are arranged in each imaging pixel.

The method for forming a color filter includes a step of forming a material to be a color filter and a step of forming the material into a desired shape. As the film forming method, there are a dry film forming method and a wet film forming method as in the case of forming the photoelectric conversion functional layer. In addition, although it is possible to form a color filter directly on the photoelectric conversion functional layer, the photoelectric conversion functional layer made of a material containing an organic semiconductor is damaged by a solvent at the time of forming the color filter. It is better to laminate a protective layer on the functional layer and form a color filter from above the protective layer. As a process for forming a desired shape, there is a method using a known photolithography technique. These steps can be adjusted by a method for forming a color filter in a known solid-state imaging device.

The photoelectric conversion element and the solid-state imaging element of the present invention can be manufactured by a process used for manufacturing a known semiconductor integrated circuit or the like. Basically, it is performed by repetitive operations such as pattern formation by photolithography and etching, diffusion layer formation by ion implantation, arrangement of element formation materials by sputtering and CVD, removal of non-patterned material, and heat treatment. Furthermore, a process and operation for forming a photoelectric conversion functional layer are added.

<< Embodiment >>
Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. Each of the following embodiments is an example used to explain the configuration of the present invention and the operations and effects produced therefrom in an easy-to-understand manner. The present invention is not limited to the following essential features. The form is not limited.

[Embodiment 1]
1. Schematic Configuration of Solid-State Image Sensor 1 As shown in FIG. 1, the solid-state image sensor 1 according to the present embodiment includes an imaging pixel region 1a and a peripheral circuit region 1b. The signal is read from the imaging pixel area 1a to the peripheral circuit area 1b and output. As shown in a portion surrounded by a two-dot chain line in FIG. 1, a plurality of imaging pixels 10 are two-dimensionally arranged in the imaging pixel region 1 a of the solid-state imaging device 1. Each imaging pixel 10 is provided with an associated color filter.

2. Configuration of each imaging pixel 10 in the solid-state imaging device 1 FIG. 2 is a schematic cross-sectional view of a part (AA ′) of the imaging pixel region 1a in FIG.

As shown in FIG. 2, an insulating layer 101, a photoelectric conversion functional layer 111, a protective layer 112, a color filter layer 112, and a top lens layer 114 are sequentially stacked on the substrate 100 from the lower side in the Z-axis direction. On the surface layer portion of the substrate 100, a charge storage portion 102 and a charge storage portion 104 are formed in a state spaced from each other in the X-axis direction. A gate electrode 103 is provided on the substrate 100 in a region corresponding to the space between the charge storage unit 102 and the charge storage unit 104. The gate electrode 103 and the charge storage portion 102 are connected to a wiring layer 105 provided in the insulating layer 101 through a contact hole 106.

A pixel electrode 107 is provided at a boundary portion between the insulating layer 101 and the photoelectric conversion functional layer 111 so as to correspond to each imaging pixel 10. A counter electrode 108 is provided in a region corresponding to the boundary between the imaging pixels 10 between the pixel electrodes 107 in the adjacent imaging pixels 10. A part of the photoelectric conversion functional layer 111 is interposed between the adjacent pixel electrode 107 and the counter electrode 108. That is, the pixel electrode 107 and the counter electrode 108 sandwich a part of the photoelectric conversion functional layer 111 in the X-axis direction.

The pixel electrode 107 and the counter electrode 108 are connected to a wiring layer 105 formed in the insulating layer 101 through contact holes 109 and 110, respectively.

The substrate 100 is preferably a silicon single crystal semiconductor substrate. The gate electrode 103 is preferably formed using polycrystalline silicon to which a voltage for reading signal charges is applied. In FIG. 2, an oxide film between the substrate 100 and the gate electrode 103 is omitted.

The charge accumulation unit 102 is a part for accumulating the signal charges generated by the photoelectric conversion functional layer 111, and the charge accumulation unit 104 accumulates the read charges by applying a voltage to the gate electrode 103. It is a part for. When electrons are taken out as signal charges from the pixel electrode 107, the charge storage portion 102 is formed by arsenic ion implantation or the like. Although not shown in FIG. 2, a p-type or n-type layer such as a well is formed in addition to the charge storage portion 102, and the read signal charge (signal voltage) is output to the outside. Transistors, contacts, wirings, and the like, which are circuits for performing the above, are formed.

The wiring layer 105 and the contact holes 106 and 109 serve as paths for signal charge transfer from the pixel electrode 107 to the charge storage unit 102 and signal voltage transmission. Tungsten is preferable as the contact material of the contact hole 106 connected to the charge storage portion 102 and the gate electrode 103, and aluminum is preferable as the contact material of the contact hole 109 connected to the pixel electrode 107.

The wiring layer 105 may have any number of layers and can be set as appropriate according to the circuit.

Aluminum is preferably used for the pixel electrode 107 and the counter electrode 108. Aluminum having a thickness of 400 [nm] is stacked over the insulating layer 101 by a sputtering method or the like, and a desired pixel electrode and counter electrode are formed thereon. A resist is formed in the planar shape pattern, and desired pixel electrodes 107 and counter electrodes 108 are formed by dry etching. The above process can be easily adjusted by a conventionally known process, a so-called CMOS process.

The photoelectric conversion functional layer 111 formed on the pixel electrode 107 and the counter electrode 108 is formed of a mixed layer of copper phthalocyanine and fullerene having broad absorption in the visible region by flash vapor deposition, and the color filters R, G, and B are formed. Each transmitted light is absorbed, and electric charge is generated by photoelectric conversion. The film thickness of the photoelectric conversion functional layer 111 is 600 [nm] from the upper surface of the insulating layer 101 and 200 [nm] from the upper surface of the pixel electrode 107.

The protective layer 112 on the photoelectric conversion functional layer 111 is made of a silicon nitride film having a thickness of 500 [nm] formed by a dry film formation method. The color filter layer 113 on the protective layer 112 is a filter having a transmission wavelength corresponding to each imaging pixel 10.

Since the photoelectric conversion functional layer 111 is protected by the protective layer 112, the color filter layer 113 is known and can be adjusted by a color filter forming process in a conventional inorganic solid-state imaging device.

3. As shown in FIG. 3, in the solid-state imaging device 1 according to the present embodiment, as shown in FIG. 3, for each imaging pixel 10, pixel electrodes arranged at intervals in the X-axis direction 107 and the counter electrode 108, and a configuration in which a part of the photoelectric conversion functional layer 111 is interposed between the electrodes 107 and 108 is employed.

For this reason, in the solid-state imaging device 1, the strongest electric field strength is applied to the photoelectric conversion functional layer 111 between the pixel electrode 107 and the counter electrode 108 (electric field lines E ₁ in FIG. 3).

On the other hand, in the photoelectric conversion functional layer 111, a relatively weak electric field strength is applied to an upper region between the pixel electrode 107 and the counter electrode 108 so as to draw an arc (electric field lines E ₂ in FIG. 3).

For this reason, high photoelectric conversion efficiency is obtained in the portion sandwiched between the pixel electrode 107 and the counter electrode 108 in the photoelectric conversion functional layer 111. Therefore, when the thickness of the photoelectric conversion functional layer 111 on the pixel electrode 107 is thin, a part of the photoelectric conversion functional layer 111 is interposed between the pixel electrode 107 and the counter electrode 108 as illustrated in FIG. It is preferable to adopt a configuration in which

Further, since a strong electric field is applied to the portion between the pixel electrode 107 and the counter electrode 108 with the shortest distance between the electrodes, it is preferable to increase the thickness of the electrodes 107 and 108 and the photoelectric conversion functional layer 111 therebetween.

[Embodiment 2]
1. Configuration of Each Imaging Pixel 11 The configuration of each imaging pixel 11 of the solid-state imaging device according to the present embodiment will be described with reference to FIG. In FIG. 4, portions having the same configuration as that of the solid-state imaging device 1 according to the first embodiment are denoted by the same reference numerals, and description thereof is omitted below.

As shown in FIG. 4, in each imaging pixel 11 of the solid-state imaging device according to the present embodiment, an insulating layer 115 is inserted between the adjacent pixel electrode 107 and the counter electrode 108 on the insulating layer 101. Yes. Note that in this embodiment mode, copper is preferably used as a constituent material of the pixel electrode 107 and the counter electrode 108.

The insulating layer 115 inserted between the pixel electrode 107 and the counter electrode 108 is not necessarily formed separately from the insulating layer 101, and may be formed of the same material. The insulating layer 101 and the insulating layer 115 are formed from the same material by a known manufacturing method with a dual damascene structure, and recesses are formed in the shapes of the desired contact holes 109 and 110, the pixel electrode 107, and the counter electrode 108. Contact holes 109, 110, a pixel electrode 107, and a counter electrode 108 are formed by sputtering, electrolytic plating, and CMP polishing. The above process can be easily adjusted by a conventionally known process, a so-called CMOS process.

The photoelectric conversion function layer 116 formed on the pixel electrode 107 and the counter electrode 108 is not interposed between the pixel electrode 107 and the counter electrode 108 by the insulating layer 115.

As described above, the photoelectric conversion functional layer 116 is formed of a mixed layer of copper phthalocyanine and fullerene having broad absorption in the visible region by flash vapor deposition, and absorbs each light transmitted through the color filters R, G, and B. Electric charges are generated by photoelectric conversion.

The film thickness of the photoelectric conversion functional layer 116 is 300 [nm] from the upper surface of the pixel electrode 107. The protective layer 112 on the photoelectric conversion functional layer 116 is formed by laminating a silicon nitride film having a thickness of 500 [nm] by a dry film forming method as described above.

2. As shown in FIG. 3, in the solid-state imaging device 1 according to the present embodiment, the pixel electrodes arranged at intervals in the X-axis direction for each imaging pixel 10. 107 and a counter electrode 108, and an insulating layer 115 is embedded between the electrodes 107 and 108 is employed.

For this reason, in the solid-state imaging device according to the present embodiment, the electric field does not concentrate in a region sandwiched between the pixel electrode 107 and the counter electrode 108, and the upper photoelectric conversion between the pixel electrode 107 and the counter electrode 108 is prevented. Since a strong electric field is also applied to the functional layer 116 (electric field lines E ₁₁ in FIG. 5), the thickness of the photoelectric conversion functional layer 116 on the electrodes 107 and 108 can be increased. A relatively weak electric field is applied further above the region between the pixel electrode 107 and the counter electrode 108 (electric field lines E ₁₂ in FIG. 5).

The distance between the pixel electrode 107 and the counter electrode 108 can be appropriately set depending on the electrode material and the forming method. However, the shorter the distance, the electric field strength between the electrodes 107 and 108 when a constant voltage is applied. Becomes stronger. Further, since the area ratio of the electrodes 107 and 108 in the imaging pixel 11 increases and the amount of reflection or absorption of incident light increases, the distance between the pixel electrode 107 and the counter electrode 108 is preferably 50 [nm] or more and 300 [ nm] or less.

[Modification 1]
In the configuration of the imaging pixel region 2a of the solid-state imaging device according to Modification Example 1, the shapes of the pixel electrode 207 and the counter electrode 208 and their arrangement will be described using FIG.

As shown in FIG. 6, in the imaging pixel region 2a according to the first modification, pixel electrodes 207 each having a square planar shape are arranged with an interval between them in both the X-axis direction and the Y-axis direction. Has been. The counter electrode 208 has a lattice shape as a whole, and is interposed between the pixel electrodes 207.

As described above, in the solid-state imaging device according to the first modification, the counter electrode 208 is arranged so as to surround the entire periphery of the pixel electrode 207 in each imaging pixel. By disposing the counter electrode 208 in this way, an electric field can be generated in all directions of the pixel electrode 207, and sensitivity can be improved.

[Modification 2]
The configuration of the pixel electrode 307 and the counter electrode 308 in the configuration of the imaging pixel region 3a of the solid-state imaging device according to Modification Example 2 and the arrangement of the counter electrode 308 will be described with reference to FIG.

As shown in FIG. 7, also in the imaging pixel region 3a according to the second modification, pixel electrodes 307 each having a square planar shape are spaced apart from each other in both the X-axis direction and the Y-axis direction. It is arranged. In the second modification, the counter electrode 308 includes a trunk portion that extends between the adjacent pixel electrodes 307 in the X-axis direction, and a branch portion 308a that extends in the Y-axis direction therefrom.

As described above, in the solid-state imaging device according to the second modification, the counter electrode 308 does not surround the entire periphery of the pixel electrode 307 in each imaging pixel but surrounds a part of the periphery. By making the counter electrode 308 independent in the Y-axis direction, the voltage applied to the counter electrode 308 can be changed, and the voltage can be set in consideration of sensitivity and power consumption in the Y-axis direction. Although not shown, the X axis and the Y axis can be the vertical direction and the horizontal direction in the planar direction of the imaging pixel region 3a, or can be the horizontal direction and the vertical direction. In this modification, a portion where the counter electrode 308 does not exist can be arranged at the staggered position, and variation due to the absence of the counter electrode can be reduced even in the peripheral portion in the vertical direction of the imaging pixel region 3a.

[Modification 3]
In the configuration of the imaging pixel region 4a of the solid-state imaging device according to Modification Example 3, the shape of the pixel electrode 407 and the counter electrode 408 and the arrangement of each other will be described with reference to FIG.

As shown in FIG. 8, also in the imaging pixel region 4a according to Modification 3, pixel electrodes 407 each having a square planar shape are spaced from each other in both the X-axis direction and the Y-axis direction. It is arranged. In the third modification, unlike the second modification, the branch portion 408 a of the counter electrode 408 is formed to extend downward in the Y-axis direction in all the counter electrodes 408.

Also in the solid-state imaging device according to Modification Example 3, as in the solid-state imaging device according to Modification Example 2, the counter electrode 408 does not surround the entire periphery of the pixel electrode 407 in each imaging pixel, but a part of the periphery. Is enclosed. By making the counter electrode 408 independent in the Y-axis direction, the voltage applied to the counter electrode can be changed, and the optimum voltage can be set in consideration of sensitivity and power consumption in the Y-axis direction. Although not shown, the X axis and the Y axis can be the vertical direction and the horizontal direction in the planar direction of the imaging pixel region 3a, or can be the horizontal direction and the vertical direction. In this modification, the three directions of the pixel electrode 407 are surrounded by the integrated counter electrode 408, and the electric field formed by one counter electrode 408 becomes more dominant than that in Modification 2, and the counter electrode The effect due to the voltage change of 408 can be increased.

[Modification 4]
In the configuration of the imaging pixel region 5a of the solid-state imaging device according to Modification Example 4, the shapes of the pixel electrode 507 and the counter electrode 508 and their arrangement will be described with reference to FIG.

As shown in FIG. 9, in the imaging pixel region 5a according to the modified example 4, the pixel electrode 507 has a portion 507a partially recessed in the Y-axis direction when seen in a plan view. It is C-shaped. The counter electrode 508 includes a branch portion 508 a that enters the portion corresponding to the portion 507 a that enters the pixel electrode 507. Other forms of the counter electrode 508 are the same as in the first modification.

In the solid-state imaging device according to Modification 4, similarly to the solid-state imaging device according to Modification 1, the counter electrode 508 surrounds the entire periphery of the pixel electrode 507 in each imaging pixel, and the branch portion 508a is the pixel electrode. Since the portion 507a that has entered into the concave shape 507 has entered, the area facing the pixel electrode 507 increases. For this reason, the area | region which generate | occur | produces an electric field spreads, and a sensitivity can be improved rather than the modification 1. FIG.

[Modification 5]
In the configuration of the imaging pixel region 6a of the solid-state imaging device according to Modification Example 5, the shape of the pixel electrode 607 and the counter electrode 608 and the arrangement thereof will be described with reference to FIG.

As shown in FIG. 10, also in the imaging pixel region 6a according to the modified example 5, the pixel electrode 607 has a portion 607a partially recessed in the Y-axis direction when seen in a plan view. Or it is C-shaped. The counter electrode 608 includes a branch portion 608 a that enters the corresponding portion 607 a in the pixel electrode 607, and a branch portion 608 b that enters between adjacent pixel electrodes 607. The branch portions 608a and 608b in the counter electrode 608 are formed to extend in directions opposite to each other in the Y-axis direction.

In the solid-state imaging device according to the fifth modification, as in the second and third modifications, the counter electrode 608 does not surround the entire periphery of the pixel electrode 607 but surrounds a part thereof. Further, when the branch portion 608a of the counter electrode 608 enters the concave portion 607a of the pixel electrode 607, the opposing regions increase. For this reason, the area | region which generate | occur | produces an electric field spreads, and a sensitivity can be improved rather than the modification 2,3. Since the branch portion 608a and the branch portion 608b are connected to different counter electrodes 608 for one pixel electrode 607, different voltages can be applied and the sensitivity can be adjusted.

[Modification 6]
In the configuration of the imaging pixel region 7a of the solid-state imaging device according to Modification 6, the shapes of the pixel electrode 707 and the counter electrode 708 and their arrangement will be described with reference to FIG.

As shown in FIG. 11, also in the imaging pixel region 7a according to the modified example 6, the pixel electrode 707 has a portion 707a partially recessed in the Y-axis direction in plan view, and has a U-shape as a whole. Or it is C-shaped. Similarly to the fifth modification example, the counter electrode 708 includes a branch portion 708a that enters the corresponding portion 707a in the pixel electrode 707, and includes a branch portion 708b that enters between adjacent pixel electrodes 707. Prepare. The counter electrode 708 according to the sixth modification differs from the fifth modification in that the branch portions 708a and 708b of the counter electrode 708 are formed to extend in the same direction in the Y-axis direction. .

Also in the solid-state imaging device according to the sixth modification, as in the fifth modification, the counter electrode 708 does not surround the entire periphery of the pixel electrode 707 but surrounds a part thereof. Further, when the branch portion 708a of the counter electrode 708 enters the concave portion 707a of the pixel electrode 707, the opposing regions increase. For this reason, the area | region which generate | occur | produces an electric field spreads, and a sensitivity can be improved rather than the modification 2,3. Since the branch portion 708a and the branch portion 708b are connected to the same counter electrode 708 with respect to one pixel electrode 707, the electric field formed by one counter electrode 708 becomes more dominant than the fifth modification. The effect due to the voltage change of the counter electrode 708 can be increased.

[Modification 7]
In the configuration of the imaging pixel region 8a of the solid-state imaging device according to the modified example 7, the shapes of the pixel electrode 807 and the counter electrode 808 and their arrangement will be described with reference to FIG.

As shown in FIG. 12, in the imaging pixel region 8a according to the modified example 7, a pixel electrode 807 corresponding to one imaging pixel is obtained by combining four electrode elements 8071, 8072, 8073, and 8074 formed adjacent to each other. Is configured. The electrode elements 8071, 8072, 8073, and 8074 are connected in the insulating layer 101 for each imaging pixel.

The counter electrode 808 has a lattice shape in plan view, and is provided between the pixel electrodes 807 and between the electrode elements 8071, 8072, 8073, and 8074 in the pixel electrodes 807.

The solid-state imaging device according to Modification 7 includes four electrode elements 8071, 8072, 8073, and 8074 in which the pixel electrode 807 is divided, and the electrode elements 8071, 8072, 8073, and 8074 are also opposed to each other. Since the electrodes 808 are interposed, the opposing areas can be further increased. For this reason, the area | region which generate | occur | produces an electric field spreads, and a sensitivity can be improved further.

[Modification 8]
In the configuration of the imaging pixel region 9a of the solid-state imaging device according to Modification Example 8, the shapes of the pixel electrode 907 and the counter electrode 908 and their arrangement with each other will be described with reference to FIG.

As shown in FIG. 13, also in the imaging pixel region 9a according to the modified example 8, a pixel electrode corresponding to one imaging pixel is obtained by combining the four electrode elements 9071, 9072, 9073, and 9074 formed adjacent to each other. 907 is configured. Also in this modification 8, each electrode element 9071, 9072, 9073, 9074 is connected within the insulating layer 101 for every imaging pixel.

This modification 8 is different from the modification 7 in that the counter electrode 908 does not surround the entire periphery of the pixel electrode 907 but surrounds a part thereof. In the counter electrode 908, the branch portion 908a is inserted between the electrode elements 9071, 9072, 9073, and 9074, and the branch portion 908b is inserted between the adjacent pixel electrodes 907. In the counter electrode 908, a branch portion 908a and a branch portion 908b are formed to extend in opposite directions in the Y-axis direction. For this reason, the area | region which generate | occur | produces an electric field spreads, and a sensitivity can be improved further. Since the branch portion 908a and the branch portion 908b are connected to different counter electrodes 908 for one electrode element, different voltages can be applied and the sensitivity can be adjusted.

[Modification 9]
In the configuration of the imaging pixel region 12a of the solid-state imaging device according to the modification 9, the shape of the pixel electrode 1207 and the counter electrode 1208 and their arrangement will be described with reference to FIG.

As shown in FIG. 14, also in the imaging pixel region 12a according to the modification 9, the pixel electrode corresponding to one imaging pixel is obtained by combining the four electrode elements 12071, 12072, 12073, and 12074 formed adjacent to each other. 1207 is configured. Also in this modification 9, each electrode element 12071, 12072, 12073, 12074 is connected in the insulating layer 101 for every imaging pixel.

Also in the solid-state imaging device according to the ninth modification, the counter electrode 1208 includes branch portions 1208a and 1208b, but is different from the eighth modification in that the extending directions thereof are the same. Since the branch portion 1208a and the branch portion 1208b are connected to the same counter electrode 1208 with respect to one electrode element, the electric field formed by one electrode element becomes more dominant than the modification example 8, and The effect due to the voltage change of the electrode 1208 can be increased.

[Embodiment 3]
1. Configuration of Each Imaging Pixel 13 The configuration of each imaging pixel 13 of the solid-state imaging device according to the present embodiment will be described with reference to FIG. In FIG. 15, a portion that is a main part of the solid-state imaging device is extracted and drawn.

As shown in FIG. 15, in the solid-state imaging device according to the present embodiment, the thickness of the counter electrode 138 in the Z-axis direction is thicker than that of the pixel electrode 107, and the pixel electrode 107 and the counter electrode 138 are between. As in the solid-state imaging device 1 according to the first embodiment, a part of 131 is inserted in a photoelectric conversion functional layer made of a material containing an organic semiconductor material.

2. Electric field strength distribution in photoelectric conversion functional layer 131 The electric field strength distribution in the photoelectric conversion functional layer 131 of the solid-state imaging device according to the present embodiment will be described with reference to FIG.

As shown in FIG. 16, in the solid-state imaging device according to this embodiment, the thickness of the counter electrode 138 with respect to the pixel electrode 107 is relatively large. A relatively strong electric field is applied to the portion between 138 (electric field lines E ₂₁ in FIG. 16), and an electric field is applied relatively upward in the Z-axis direction in the photoelectric conversion functional layer 131 (electric field lines in FIG. 16). E ₂₂ ), and the photoelectric conversion characteristics can be improved.

3. Manufacturing Method A characteristic part during the manufacturing process of the solid-state imaging device according to the present embodiment will be described with reference to FIGS. In FIGS. 17 and 18, for the sake of simplification of the drawings, wiring and contact holes other than the contact hole 109 connected to the charge accumulation portion, the gate electrode, and the pixel electrode in and on the substrate 100 are illustrated. Omitted. The manufacturing method up to the formation of the insulating layer 101 and the contact hole / wiring layer is the same as that described in the second embodiment.

As shown in FIG. 17A, a contact hole 101a is formed in the insulating layer 101 at a location where a contact hole connected to the pixel electrode 107 is to be formed.

As shown in FIG. 17B, after the contact hole 101a is formed, a resist film 500 is deposited on the insulating layer 101 in a region where the pixel electrode 107 is not to be formed. Subsequently, copper that is a constituent material of the contact material and the pixel electrode 107 is laminated to form a metal film 1070. In FIG. 15 and the like, for the sake of convenience, the pixel electrode 107 and the contact material of the contact hole 109 therebelow are used as different hatching types. However, as described above, the constituent material of the pixel electrode 107 and the contact material are the same. And

Further, when the thickness of the pixel electrode 107 is 300 [nm], the thickness of the metal film 1070 is preferably 300 [nm] or more and 350 [nm] or less.

Next, the upper portions of the metal film 10702 and the resist film 500 are polished and removed by CMP polishing so as to obtain a desired pixel electrode film thickness. Then, by removing the remaining resist film 500, the pixel electrode 107 and the contact hole 109 are formed as shown in FIG. The film thickness of the pixel electrode 107 is 300 [nm] from the upper surface of the insulating layer 101, which is the same as the desired film thickness of the pixel electrode 107.

On the insulating layer 101 and the pixel electrode 107, a resist film 501 patterned in accordance with a region where the counter electrode 138 is not to be formed is disposed. Subsequently, a metal film 1380 to be the counter electrode 138 is stacked (see FIG. 18A). Here, the metal film 1380 is also formed of copper, and the film thickness is equal to or greater than the desired film thickness of the counter electrode 138. When the thickness of the counter electrode 138 is set to 500 [nm], the thickness of the metal film 1380 is preferably 500 [nm] to 600 [nm].

The upper part of the metal film 1380 and the resist film 501 is polished and removed by CMP polishing so that the desired counter electrode film thickness is obtained. By removing the remaining resist film 501, a counter electrode 138 is formed as shown in FIG.

Note that the thickness of the counter electrode 138 becomes 500 [nm] from the upper surface of the insulating layer 101 in the stage shown in FIG. 18B, and is the same as the desired thickness of the counter electrode 138. The above process can be adjusted by a conventionally known process, a technique in a so-called CMOS process.

Thereafter, although not shown, the photoelectric conversion functional layer 131 is formed using an organic semiconductor material. The photoelectric conversion functional layer 131 is formed by stacking as a mixed layer of copper phthalocyanine and fullerene having broad absorption in the visible region by flash vapor deposition.

The film thickness of the photoelectric conversion functional layer 131 is preferably thicker than the counter electrode 138, and is set to 700 [nm]. The solid-state imaging device according to the third embodiment is manufactured by the manufacturing method as described above.

[Embodiment 4]
The configuration of the solid-state imaging device according to Embodiment 4 will be described with reference to FIG. FIG. 19 shows an essential part of the solid-state imaging device according to the fourth embodiment.

As shown in FIG. 19, in the solid-state imaging device according to the present embodiment, in each imaging pixel 14, the pixel electrode 107 and the counter electrode 148 are arranged facing each other in a direction intersecting the Z-axis direction. ing. In the solid-state imaging device according to the present embodiment, the pixel electrode 107 is formed on the surface of the insulating layer 101 as in the first embodiment, while the counter electrode 148 has the insulating layer 101. An insulating layer or a photoelectric conversion functional layer 141 is interposed between the two surfaces.

In this way, by disposing the counter electrode 148 so as to be shifted upward in the Z-axis direction, a large amount of light generated in the upper portion of the photoelectric conversion functional layer 141 in the Z-axis direction is effectively transferred to the pixel electrode 107. It becomes possible to read in, and the sensitivity characteristic can be further enhanced.

The present invention is useful for realizing a low-cost digital still camera or digital movie camera including a solid-state imaging device having high sensitivity.

1. Solid- state imaging devices 1a, 2a, 3a, 4a, 5a, 6a, 7a, 8a, 9a, 12a. Imaging pixel area 1b. Peripheral circuit area 10, 11, 13, 14. Imaging pixel 100. Substrate 101. Insulating layer 102. Charge storage unit 103. Gate electrode 104. Charge storage unit 105. Wiring layer 106,109,110. Contact hole 107,207,307,407,507,607,707,807,907,1207. Pixel electrodes 108, 138, 148, 208, 308, 408, 508, 608, 708, 808, 908, 1208. Counter electrode 111,116,131,141. Photoelectric conversion functional layer 112. Protective layer 113. Color filter layer 114. Top lens layer 115. Insulating layer 500,501. Resist films 1070, 1380. Metal films 8071, 8072, 8073, 8074, 9071, 9072, 9073, 9074, 12071, 12072, 12073, 12074. Pixel electrode elements E ₁ , E ₂ , E ₁₁ , E ₁₂ , E ₂₁ , E ₂₂ . Electric field lines

Claims (20)

1. A substrate, a photoelectric conversion functional layer formed above the substrate and including an organic semiconductor material, and a first electrode and a second electrode both provided in contact with an interface of the photoelectric conversion functional layer; A photoelectric conversion element comprising:
   The first electrode is in contact with the interface on the substrate side in the photoelectric conversion functional layer;
   The first electrode and the second electrode are opposed to each other in a direction intersecting the thickness direction of the substrate.
2. The photoelectric conversion functional layer is formed in a state of covering an upper surface and a side surface of the first electrode,
   2. The photoelectric conversion according to claim 1, wherein the second electrode is arranged so as to surround at least a part of the periphery of the first electrode in a direction intersecting the thickness direction of the substrate. element.
3. The first electrode is composed of a plurality of electrode elements spaced from each other in a direction along the main surface of the substrate,
   2. The photoelectric device according to claim 1, wherein the second electrode is arranged so as to surround at least a part of the plurality of electrode elements in a direction intersecting a thickness direction of the substrate. Conversion element.
4. The photoelectric conversion element according to claim 2, wherein the first electrode is not covered with the second electrode in the thickness direction of the substrate.
5. 2. The photoelectric conversion layer according to claim 1, wherein the photoelectric conversion functional layer includes a photoelectric conversion layer and has a stacked structure including at least one of an electron transport layer and a hole transport layer. element.
6. The photoelectric conversion element according to claim 1, wherein the surface of at least one of the first electrode and the second electrode is a light reflecting surface.
7. The photoelectric conversion element according to claim 1, wherein a protective layer for protecting the photoelectric conversion functional layer is laminated on the photoelectric conversion functional layer in the thickness direction of the substrate.
8. The photoelectric conversion element according to claim 1, wherein in the thickness direction of the substrate, a color filter layer made of an organic material is stacked above the photoelectric conversion functional layer.
9. The photoelectric conversion element according to claim 1, wherein in the thickness direction of the substrate, the layer thickness of the second electrode is larger than the layer thickness of the first electrode.
10. A solid-state imaging device having a plurality of imaging pixel units arranged two-dimensionally,
    Each of the plurality of imaging pixel units is formed to include the configuration of the photoelectric conversion element according to any one of claims 1 to 9. A solid-state imaging element.
11. Forming a first electrode and a second electrode in a state of facing each other in a direction intersecting the thickness direction of the substrate above the substrate;
    Forming a photoelectric conversion functional layer in a state in contact with both the first electrode and the second electrode using a material containing an organic semiconductor material;
    A process for producing a photoelectric conversion element, comprising:
12. In the step of forming the first electrode and the second electrode, the second electrode is formed so as to surround at least a part of the periphery of the first electrode in a direction intersecting the thickness direction of the substrate. ,
    The method for producing a photoelectric conversion element according to claim 11, wherein in the step of forming the photoelectric conversion functional layer, the photoelectric conversion functional layer is formed in a state of covering an upper surface and a side surface of the first electrode.
13. In the step of forming the first electrode and the second electrode,
    Forming the first electrode with a plurality of electrode elements formed in a state spaced apart from each other in a direction along the main surface of the substrate;
    The method for manufacturing a photoelectric conversion element according to claim 11, wherein the second electrode is formed so as to surround at least a part of the plurality of electrode elements in the first electrode.
14. 13. The step of forming the first electrode and the second electrode forms the second electrode so as not to cover the upper side of the first electrode in the thickness direction of the substrate. Manufacturing method of the photoelectric conversion element.
15. In the step of forming the photoelectric conversion functional layer, the photoelectric conversion functional layer is formed with a laminated structure including a photoelectric conversion layer and at least one of an electron transport layer and a hole transport layer. The manufacturing method of the photoelectric conversion element in any one of Claims 11-14.
16. In the step of forming the first electrode and the second electrode, at least one of the first electrode and the second electrode is formed so that a surface thereof is a light reflecting surface. The manufacturing method of the photoelectric conversion element of description.
17. The process for stacking a protective layer for protecting the photoelectric conversion functional layer on the photoelectric conversion functional layer in the thickness direction of the substrate is provided. Method.
18. The method for producing a photoelectric conversion element according to claim 11, further comprising a step of stacking and forming a color filter layer above the photoelectric conversion functional layer in the thickness direction of the substrate using an organic material.
19. In the step of forming the first electrode and the second electrode, the second electrode is formed so that its layer thickness in the thickness direction of the substrate is thicker than that of the first electrode. Item 12. A method for producing a photoelectric conversion element according to Item 11.
20. A method of manufacturing a solid-state imaging device having a plurality of imaging pixel units arranged two-dimensionally,
    Each of these image pick-up pixel parts is formed with the manufacturing method of the photoelectric conversion element in any one of Claims 11-19. The manufacturing method of the solid-state image sensor characterized by the above-mentioned.

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